Combined centrifugal and magnetic separator mechanism



Oct. 20, 1970 E. GILREATH 3,534,902

COMBINED CENTRIFUGAL AND MAGNETIC SEPARATOR MECHANISM Filed Feb. 7, 1969 i Lafayette EG/lreczth & INVENTOR 3 i7 to [i 5 N BY z ATTORNEY 3,534,902 COMBINED CENTRIFUGAL AND MAGNETIC SEPARATOR MECHANISM Lafayette E. Gilreath, 7623 Arnim St., Houston, Tex. 77017 Filed Feb. 7, 1969, Ser. No. 797,652 Int. Cl. B0411 1/20 US. Cl. 233-7 9 Claims ABSTRACT OF THE DISCLOSURE A centrifugal separator of the type having an elongated barrel mounted for rotation about its longitudinal axis and an elongated rotor mounted for rotation in the barrel about the same axis and provided with a spiral flight extending from end to end thereof to form with the barrel a spiral passageway.

The barrel and rotor are adapted to be rotated in the same direction at different speeds to cause solids separated by centrifugal action to be moved toward one end of the barrel while allowing the flow of liquid through the passageway toward the other end of the barrel. Magnetic means in the form of a portion of the barrel formed of permanent magnetic material or an electromagnetic coil surrounding a portion of the barrel which is formed of magnetic material, is provided for attracting magnetic particles in the material under treatment and holding the same at a location to be moved along the barrel by the flight of the rotor.

BACKGROUND OF THE INVENTION In the centrifugal separation of solids from liquids, and especially in the carrying out of such separation on a large scale by a continuous operation, such as by the use of centrifugal apparatus of the rotating barrel and rotor type in which the rotor is provided with a spiral flight forming a spiral passageway between the rotor and barrel through which separated solids are propelled toward one end of the barrel while liquid may flow therethrough toward the other end of the barrel, it has been found that very fine particles of some kinds of materials suspended in liquid are very difficult, if not impossible to separate therefrom by the operation of such equipment in the usual manner.

Thus, very fine particles of sulfur may form in liquids a suspension having colloidal properties such that they cannot be separated from the liquid by the use of a centrifugal separator of the type mentioned. Other material, such as the fine particles of stack dust, found in the liquid obtained from the washing of stack gases is not readily removed by ordinary centrifugal separation methods.

It has been proposed heretofore to effect removal of very small particles of solids, too small to be readily separated from liquids by the use of centrifugal separators of the type referred to, by adding finely divided relatively heavy material, such as fine iron dust, and subjecting the mixture so formed to a magnetic field to centrifugal action to remove the same along with the other finely divided material not readily removed by centrifugal means. The use of fine metallic, or other heavy particles in this manner, has not proven to be fully effective, since such materials may themselves become so dispersed in the liquid that they are not removed by centrifugal action. Dispersions resistant to centrifugal separation may, for example, be formed when the liquid phase of the material under treatment reacts with the added particles to produce products tending to increase dispersion or to reduce the size of the added particles.

It has now been discovered that improved results may be obtained in the separation of dispersions containing United States Patent 3,534,962 Patented Oct. 20, 1970 ice finely divided particles of magnetic material, such as powdered iron, by subjecting such a dispersion to a strong magnetic field during the centrifuging of the dispersion, whereby such magnetic material is caused to separate from the liquid in a condition to be readily removed from the centrifuge.

In the case of materials, such as that obtained from the washing of flue gases or the recovery of stack dust, such materials often already contain finely divided particles of iron in suflicient amount to permit the removal of the solids by subjecting the same to a strong magnetic field during the centrifuging of the material. Under some circumstances, when there is insufiicient magnetic material in the material under treatment to provide effective separation of the solids, finely divided magnetic material, such as powdered iron may be added prior to subjecting the material to centrifugal and magnetic treatment.

SUMMARY OF THE INVENTION Briefly described, the centrifugal and magnetic separator mechanism of the invention comprises a centrifuge of the type having a rotatably mounted barrel within which a rotor is mounted which is provided with a spiral flight forming with a barrel, a spiral passageway through which separated solids may move toward one end of the barrel while separated liquid may flow therethrough toward the other end of the barrel. The barrel and rotor are adapted to be rotated in the same direction, but at different speeds whereby the separated solids are propelled in one direction along the barrel while allowing the flow of liquid in the other direction.

The barrel has a discharge outlet at each end thereof and inlet means is provided for introducing the material under treatment into the barrel at a location mediate the ends of the barrel.

The barrel may be formed partly of entirely of nonmagnetic material, such as non-magnetic stainless steel, or other suitable non-magnetic material and means is provided for subjecting the separated liquid in the barrel to a strong magnetic field to cause the removal therefrom of magnetic particles not previously removed by centrifugal action.

The magnetic field may be produced by a permanent magnet which forms a part of the barrel located between the inlet and the end of the barrel at which the separated liquid is discharged, while the remainder of the barrel is formed of non-magnetic material.

On the other hand the magnetic may be produced by a electromagnetic coil surrounding the barrel between the inlet and the liquid discharge outlet, and the portion of the barrel surrounded by the coil may be of magnetic material to form a hollow core for the same, or this portion may be of non-magnetic material.

By this arrangement the particles of magnetic material remaining in the separated liquid may be made to move toward the suirounding wall of the barrel under the influence of the combined centrifugal and magnetic effect, so that the solid material may then be moved by the flight of the rotor toward the solids discharge outlet of the barrel, while the liquid may flow out of the liquid outlet.

BRIEF DESCRIPTION OF THE VIEWS OF THE DRAWINGS FIG. 1 is a central, longitudinal, cross-sectional view of a preferred embodiment of the centrifugal and magnetic separator of the invention; and

FIG. 2 is a fragmentary view, similar to that of FIG. 1, illustrating a modified form of the separator mechamsm.

DETAILED DESCRIPTION OF A PARTICULAR EMBODIMENT OF THE INVENTION Referring now to the drawings in greater detail the separator mechanism of the invention comprises an elongated barrel closed at one end by a cover or end plate 12, formed with a central, tubular extension 14 to provide a bearing shaft or hub for one end of the barrel, and having at its other end a cover plate 16 formed with a central tubular extension 18 whose outer end portion 20 provides a bearing shaft for the other end of the barrel.

The shaft 14 is rotatably supported on a suitable bearing 22 mounted on a fixed support, such as a pillow block 24, and the shaft 20 is similarly supported on a pillow block 26, the blocks being carried on a suitable support structure, not shown, in the usual manner to support the apparatus for high speed rotation about its longitudinal axis.

The shaft portion 18 of the cover plate 16 is enlarged and the plate has an internal, central, tubular extension 28 to provide an inwardly opening counterbore within which suitable bearings 30 and 32 are located to rotatably support a central operating shaft 34 extending through the extension 18 and which is connected at its inner end to the inner rotor 36 of the apparatus.

The barrel 10 may be formed with a tapering wall portion 38 having at its larger end an external annular flange 40 for the attachment thereto of a straight tubular section 42, as by means of an external annular flange 44, which straight tubular portion may be provided with another external annular flange 46 at its other end for the connection thereto of the cover 16.

The rotor 36 is of elongated configuration to fit within the barrel and has a tapered tubular portion 48 located within the tapered portion 38 of the barrel and a straight tubular poriton 50 located within the straight tubular portion 42 of the barrel. The portions 48 and 50 make up a central or core portion of the rotor which is formed with an external spiral flight 52 extending from end to end of the rotor and which fits the internal surface of the barrel wall closely to form therewith a spiral passageway 54.

The rotor 36 extends from end to end of the barrel between the closures or cover plates .12 and 16, there being only sufi icient clearance between the barrel and rotor to allow the rotor to rotate freely in the barrel.

The rotor has at its larger end an end counterbore 56 which fits over the internal extension 28 of the closure plate 16, and the rotor is rotatably supported at its smaller end on an inner tubular shaft 58 on the cover plate 12, as by means of bearings 60 and 62.

An inlet pipe 64 extends through the tubular shafts 14 and 58 of cover plate 12 into an inlet chamber 66 formed in the interior of the rotor and through which material to be treated is introduced into the apparatus. From the inlet cavity of the rotor the material to be treated may flow into the spiral passageway 54 through openings 68 in the rotor mediate the ends thereof. At its outer end the inlet pipe is connected to a supply line 70 through which the material to be treated is supplied to the apparatus.

At the larger end of the barrel the cover plate 16 is provided with outlet openings 72 in communication with the passageway 54 and through which the separated liquid may flow from the apparatus, and the barrel is provided at its smaller end with one or more outlets, such as that shown at 74 through which separated solids are discharged from the passageway 54.

The shaft 14 may be provided outwardly beyond the pillow block 24 with a driving pulley 7 6 or other suitable means by which the barrel may be rotated from any suitable source of power, and the extension shaft '18 may be provided with similar driving means, such as the sprocket 78, or the like, by which the rotor 36 may be rotated from such power source.

The portion 38 of the barrel may be formed of nonmagnetic stainless steel, while the tubular section 42 thereof may be of magnetic material such as steel or magnetic iron of a suitable grade to form a core for an electromagnetic coil 30 wound about the tubular section between the attaching flanges 44 and 46 thereof, and which may be supplied with electric current from any suitable source to energize the coil to produce a magnetic field to attract particles of magnetic material carried in the separated liquid in the barrel.

In the operation of the apparatus the material under treatment is introduced into the rotor through pipe 64 while the barrel and rotor are being rapidly rotated in the same direction at slightly different speeds, so that the flight 52 is turned to feed solid materials toward the solids outlet end of the barrel. The material under treatment will then enter the passageway 54 through openings 68 wherein solids will be separated therefrom by centrifugal action and moved along the wall of the barrel by the flight 54 to be discharged through outlet 74.

Liquid separated from the solids will then flow through the passageway 54 toward the large end of the barrel and out through outlets 72. As the separated liquid passes through the tubular section 42 it will be subjected to a strong magnetic field, which causes any magnetic particles remaining in the liquid to be attracted toward the wall of the barrel while being at the same time subjected to centrifugal action, so that such particles will be effectively separated from the liquid to be moved along the barrel by the flight 52 to the solids discharge end of the barrel.

It will be seen that the centrifugal separator thus constructed has a main solids separation zone extending from the vicinity of the inlets 68 to the solids discharging end of the barrel, and a liquid outflow zone extending from the inlet zone to the liquid discharging end of the barrel. These zones may, of course, overlap to a considerable extent, and are not necessarily sharply defined, but may vary considerably in extent with changes in the character of the material under treatment and conditions under which the apparatus is operated.

The portion of the barrel in which the separated liquid is subjected to the influence of the magnetic field produced by the coil 86 may also be regarded as a zone of separation of magnetic particles from the liquid.

Under some circumstances, such as when the solids remaining in the separated liquid are non-magnetic and of a colloidal nature, or in a state of subdivision which prevents them from being separated by the apparatus in normal use, magnetic material, such as iron dust or other finely divided magnetic material may be added to the material under treatment before it is introduced into the the apparatus, so that the magnetic material will be separated from the liquid by the aid of the magnetic field and will carry with it all or a substantial part of the suspended non-magnetic material, thus greatly improving the efliciency of the apparatus.

A somewhat different form of the invention is illustrated in FIG. 2, wherein the straight tubular section 42 of the barrel is formed of permanent magnetic material, such as Alnico, magnetic ceramic material or the like, capable of producing a strong permanent magnetic field.

In other respects the form of the apparatus illustrated in FIG. 2 is similar to and operates in a similar manner to that illustrated in FIG. 1.

It will thus be seen that the invention provides centrifugal separator mechanism of simple design and rugged construction by which suspended particles too small to be readily removed from a liquid suspension of such particles by subjecting the same to the usual centrifugal action of such apparatus may be subjected to the combined eflect of centrifugal action and magnetic force to effect separation of the same.

The invention is disclosed herein in connection with particular embodiments of the same, which are intended to be illustrative only, it being evident that 'various changes in the construction and arrangement of the parts can be made within the spirit of the invention and the scope of the appended claims.

Having thus clearly shown and described the invention, what is claimed as new and desired to secure by Letters Patent is:

1. In a centrifugal separator a hollow barrel having longitudinally spaced outlets, a rotor in the barrel, means supporting the barrel and rotor for rotation at different speeds about a common longitudinal, central axis, means on said rotor forming a spiral passageway between the rotor and barrel in communication with said outlets, inlet means for introducing a material to be treated into said passageway mediate said outlets and magnetic means positioned to exert a magnetic force on particles of magnetic material in a liquid in said passageway between said inlet means and one of said outlets to urge the particles toward the internal surface of the barrel.

2. The centrifugal separator as claimed in claim 1, wherein said passageway forming means is a spiral flight formed on said rotor for rotation therewith upon rotation of said barrel and rotor at different speeds in the same direction to move solids separated from said material toward one of said outlets while allowing the flow of liquid in the passage toward the other of said outlets, and wherein said magnetic means is positioned between said inlet means and said other of said outlets.

3. The centrifugal separator as claimed in claim 1, wherein said magnetic means is formed of permanent magnetic material.

4. The centrifugal separator as claimed in claim 1, wherein said magnetic means includes an electromagnetic coil.

5. The centrifugal separator as claimed in claim 1, wherein said barrel has a portion formed of non-magnetic material extending from said inlet means to one end of the barrel, and a portion formed of magnetic material extending from said non-magnetic portion to the other end of said barrel.

6. The centrifugal separator as claimed in claim 5, wherein said magnetic portion of the barrel is formed of a permanent magnetic material.

7. The centrifugal separator as claimed in claim 1 wherein said magnetic means includes a portion of said barrel formed of magnetic material located between said inlet means and one end of the barrel, and an electromagnetic coil surrounding said magnetic portion.

8. In a centrifugal separator a hollow barrel having longitudinally spaced outlets, a rotor in the barrel, means supporting the barrel and rotor for rotation at different speeds about a common longitudinal, central axis, means on the rotor forming a spiral passageway between the rotor and barrel in communication with said outlets, means for introducing into said passageway between said outlets a fluid suspension of solid particles of magnetic material suspended in a liquid, said particles being of a size to remain suspended in the liquid when said suspension is subjected in the passageway to centrifugal action produced by such rotation of the barrel and rotor, and means for producing a magnetic field in said passageway through which said suspension may flow toward one of said outlets to apply a force to said particles urging the particles toward the surrounding wall of the barrel.

9. In a centrifugal separator a hollow barrel having longitudinally spaced outlets, a rotor in the barrel, means supporting the barrel and rotor for rotation at different speeds about a common longitudinal, central axis, flight means on the rotor forming a spiral passageway between the rotor and barrel in communication with said outlets, means for introducing into said passageway between said outlets a fluid suspension of particles of magnetic and non-magnetic materials suspended in a liquid, some of said particles being of a size to be separated from the liquid when the suspension is subjected to centrifugal action produced by such rotation of the barrel and rotor and to be moved by said flight means toward one end of the barrel when so separated and some of said particles including some of said particles of magnetic material being of a size to remain suspended in the liquid when the suspension is subjected to such centrifugal action and to move with the liquid toward the other end of the barrel, and magnetic means positioned to apply a force to said magnetic particles remaining suspended in the liquid during the flow of said liquid toward said other end to cause said remaining particles to move toward the surrounding Wall of the barrel.

References Cited UNITED STATES PATENTS 1,527,069 2/1925 Peck 2337 X 1,527,070 2/ 1925 Peck 233-7 X 3,428,248 2/1969 Andresen et a1 2337 3,447,742 6/1969 Eriksson et a1. 233-7 FOREIGN PATENTS 687,712 4/1930 France.

WILLIAM I. PRICE, Primary Examiner 

